Field of the Invention
The present invention relates to an electronic device, to a multimedia device, and to a method of manufacturing an electronic device.
Description of the Related Art
Silicon microphones may be manufactured from a solid block of crystalline silicon material which, by applying techniques such as etching and using sacrificial layers, are processed so as to form two opposing membranes on the annular block which are connected with metallic electrodes. In the presence of acoustic waves, the membranes move, thereby changing the capacitance of the membrane-electrode arrangement which can be measured electrically via an electric signal between the electrodes. Such silicon microphones can be mounted together with a logic chip (such as an ASIC, application specific integrated circuit) in a semiconductor casing having an inlet for the acoustic waves.
The volume within the casing which opposes the acoustic wave inlet and which is partially delimited by the membranes can be denoted as back volume and significantly influences the performance of the microphone. A high back volume results in a high signal-to-noise ratio, and vice versa. The size of the back volume required for a proper performance is correlated to the size of the silicon microphone. Hence, the performance requirement directly translates into a high area consumption of the silicon microphone on a printed circuit board. At the same time, there is a continued trend towards smaller dimensions of electronic members (for instance in case of a silicon microphone, a maximum height of less than 1 mm is desired).
Thus, such height requirements contradict to the performance requirements. In other words, there is a technology-related contradiction between miniaturization and performance of silicon microphones.